Chronic heel pain is one of the most common types of pain affecting the human body. It is estimated that over six million people in the United States develop this condition every year. Traditional treatments for such chronic heel pain include cortisone injections, oral anti-inflammatory medications, shoe inserts, and physical therapy. If such conservative treatments do not provide relief to the patient, surgery is often the only effective treatment.
The most common cause of heel and arch pain is a condition called plantar fasciitis (heel pain). This is an inflammation of a thick, fibrous band of tissue, called the plantar fascia, that runs along the arch of the foot from the heel to the toes, and aids in stabilization of the arch during walking and running. Symptoms may involve one or both of the arch and the inside heel area.
Plantar fasciitis is caused by a mechanical imbalance in the foot called pronation. Over-pronation causes the foot to roll in towards the arch and big toe area. The plantar fascia inserts in the heel bone and then spreads out and joins the toes. When the foot rolls in (pronates) the plantar fascia must try and stretch, but it cannot. Therefore, the fascia pulls at its insertion at the heel bone. In extreme cases, this pulling Causes plantar fasciitis, a painful and often debilitating condition.
There have been numerous studies reporting various success rates for conservative care treatments for chronic heel pain. Even with the high success rate of conservative care, a percentage of heel pain patients eventually become surgical candidates. Historically, a wide range of “open” techniques have been used to perform plantar fasciotomies. More recently, endoscopic techniques, which can be performed through one or two small incisions, have been used to perform less invasive plantar fasciotomies. Studies of these endoscopic techniques have shown a substantial reduction in post-operative morbidity and amount of time needed to return to normal activities when compared to traditional “open” techniques.
One such endoscopic technique for the performance of plantar fasciotomies is shown and described by McNamara et al. in U.S. Pat. No. 5,620,446. The device shown in the '446 patent includes a cutting instrument with a knife blade with a palpation end to sever tissue without snagging while palpating underlying tissue. The instrument comprises an elongated shaft having proximal and distal ends, a handle secured to the proximal end for use in manipulating the instrument, and the distal end having a generally blunt forward portion extending at an angle from the shaft and including an excising portion generally facing the proximal end of the shaft. In using the instrument, a sleeve is driven into the patient's foot from a medial aspect to a lateral aspect of the heel, i.e. entirely through the patient's foot. Visualization is made through the use of an arthroscopic camera, which is introduced through an open end of the sleeve on the medial aspect of the foot. The other open end of the sleeve is used as a working portal for the introduction of various surgical instruments to operate caudally on the line of insertion.
While this technique may have advantages over previous, more invasive techniques, it still requires incisions on both sides of the heel, and the sleeve must be large enough to accommodate both the camera and the cutting instrument, which in itself creates a trauma to the patient's foot and heel. Further, the instrument is expressly designed for the entire excision of the plantar fascia. It is known that excision part way, for example half way, through the plantar fascia is often sufficient for the complete relief of the patient's chronic heel pain.
Barrett et al., in U.S. Pat. No. 5,269,290, describe an endoscopic plantar fasciotomy procedure to relieve the symptoms of heel spur syndrome. A small, vertical incision is made in the medial side of the foot, and the adipose tissue is spread. A fascial elevator is inserted into the first incision to separate the plantar fascia from the surrounding tissue, creating a channel. A slotted canula and trocar are inserted into the channel, and a second incision is made on the lateral side of the foot, allowing the canula and trocar to substantially pierce the foot. The trocar is removed, and an endoscope is inserted into the canula through the medial portal. A cutting instrument is inserted into the lateral portal of the canula, and is used to release the plantar fascia from the heel bone. This procedure, like others in the art, suffer the drawbacks in that (1) incisions must be made on both sides of the foot; (2) the instruments must be made large enough to accommodate the endoscope; and (3) the instrument is designed to cut entirely through the plantar fascia, where cutting partially through the fascia would relieve the patient's pain.
Less invasive instruments have been proposed for other surgical techniques. For example, Strickland et al., in U.S. Pat. No. 6,179,852, describe a carpal tunnel device and method for carpal tunnel release surgery. However, the physiological structure in around the heel are quite different than those of the hand, and thus the capture clip is not well suited for the foot and heel. Further, as with the McNamara device, the Strickland instrument is used to completely divide the carpal ligament.
Thus, there remains a need for a technique and an instrument for performing plantar faciotomies that is less invasive than known techniques and instruments. The present invention is directed to such a technique and such an instrument.
Another source of chronic pain in the foot is Morton's neuroma. A neuroma is a benign tumor of a nerve. Morton's neuroma is not actually a tumor, but a thickening of the tissue that surrounds the digital nerve leading to the toes. It occurs as the nerve passes under the ligament connecting the toe bones (metatarsals) in the forefoot. Morton's neuroma most frequently develops between the third and fourth toes, usually in response to irritation, trauma, or excessive pressure. Treatment of this condition usually begins with shoewear adaptations. Sometimes simply moving to a wider shoe will reduce or eliminate the symptoms. An injection of xylocalne and cortisone into the area may help temporarily. If this fails to resolve the pain, surgery may be suggested. Surgery has traditionally involved removing the neuroma, and since the neuroma is part of the nerve, the nerve is removed as well. This results in permanent numbness in the area supplied by the nerve. Thus, there remains a need for a surgical instrument and a technique for treating Morton's neuroma which would eliminate the necessity of removing the neuroma, and therefor the nerve. The present invention is also directed to satisfying this need in the art.